Juan Luis Gutiérrez-Chico

Impact of Side Branch Modeling on Computation of Endothelial Shear Stress in Coronary Artery Disease: Coronary Tree Reconstruction by Fusion of 3D Angiography and OCT.

BACKGROUNDnComputational fluid dynamics allow virtual evaluation of coronary physiology and shear stress (SS). Most studies hitherto assumed the vessel as a single conduit without accounting for the flow through side branches.nnnOBJECTIVESnThis study sought to develop a new approach to reconstruct coronary geometry that also computes outgoing flow through side branches in hemodynamic and biomechanical calculations, using fusion of optical coherence tomography (OCT) and 3-dimensional (3D) angiography.nnnMETHODSnTwenty-one patients enrolled in the DOCTOR (Does Optical Coherence Tomography Optimize Revascularization) fusion study underwent OCT and 3D-angiography of the target vessel (9 left anterior descending, 2 left circumflex, 10 right coronary artery). Coronary 3D reconstruction was performed by fusion of OCT and angiography, creating a true anatomical tree model (TM) including the side branches, and a traditional single-conduit model (SCM) disregarding the side branches.nnnRESULTSnThe distal coronary pressure to aortic pressure (Pd/Pa) ratio was significantly higher in TMs than in SCMs (0.904 vs. 0.842; pxa0< 0.0001). Agreement between TM and SCM in identifying patients with a Pd/Pa ratioxa0≤0.80 underxa0basal flow conditions was only kxa0= 0.417 (pxa0= 0.019). Average SS was 4.64 Pascal lower in TMs than in SCMs (pxa0<xa00.0001), with marked differences in the point-per-point comparison, ranging from -60.71 to 7.47 Pascal.nnnCONCLUSIONSnTrue anatomical TMs that take into account the flow through side branches are feasible for accurate hemodynamic and biomechanical calculations. Traditional SCMs underestimate Pd/Pa and are inaccurate for regional SSxa0estimation. Implementation of TMs might improve the accuracy of SS and virtual fractional flow reserve calculations, thus improving the consistency of biomechanical studies.

Optical coherence tomography imaging after successful percutaneous coronary intervention treatment of coronary perforation following bioabsorbable vascular scaffold implantation: Consecutive ping-pong and child-in-mother techniques

Received: 07.07.2016 Accepted: 25.07.2016 Optical coherence tomography imaging after successful percutaneous coronary intervention treatment of coronary perforation following bioabsorbable vascular scaffold implantation: Consecutive ping-pong and child-in-mother techniques Carlos Cortés, Ignacio J. Amat-Santos, Milosz Jaguszewski , Paol Rojas, L. Renier Gonçalves, Juan Luis Gutiérrez-Chico , J. Alberto San Román

Off-label indications for bioresorbable scaffolds: "Beethoven can, but you cannot".

The pianist Carl Czerny, a pupil of Beethoven, reports in his book On the Proper Performance of all Beethovens Works for the Piano an interesting anecdote. The young Anton Halm presented the master a sonata that he had just composed. Beethoven looked through it without finding anything that aroused his attention and after a few minutes gave the young composer his piece back, remarking that he had contravened several elementary rules of harmony. The young Halm protested: “But Beethoven himself also infringes the same rules of harmony!” Then the genius turned to him with a fulminating glance and declared: “Beethoven can, but you cannot”. n nWe should remember this motto whenever we consider off-label indications for novel devices or novel therapeutic options in general: “Beethoven can, but WE cannot”. The excess of self-assurance and overconfidence in our own capabilities is most likely behind the poorer-than-expected clinical performance of bioresorbable scaffolds (BRS) after becoming widely available [1], at variance with the outstanding promising results reported in pilot studies [2–4]. Therefore putting ourselves in the pupils shoes is always the advisable starting point to face an off-label indication for BRS. n nNonetheless, potential off-label indications pop up daily in our routine clinical practice, and we are compelled to explore them if we aim to optimise the treatment of our patients and the potential of the emerging technology. The motto “Beethoven can, but you cannot” is the best possible starting point, but it can never become an excuse to brake the expansion of novel therapeutic tools into more challenging scenarios, in which they may also be convenient and useful. In a recent number of Advances in Interventional Cardiology, our colleagues from Katowice, namely Roleder T, Wanha W, Smolka G, Zimoch J, Ochala A and Wojakowski W publish a modest but interesting descriptive study entitled “Bioresorbable vascular scaffolds in saphenous vein graft disease. Pilot results from the OCTOPUS registry” [5]. It is just a descriptive series of 6 patients undergoing percutaneous coronary intervention (PCI) with implantation of the Absorb BRS (Abbott Vascular, Santa Clara, CA) in saphenous vein grafts, but very relevant to expand the indication of the BRS to this challenging (still off-label) scenario. To date there have been several case reports of BRS implanted in saphenous vein grafts [6, 7], some of them reported by the same authors of the current study [8], but this is the first systematic series specifically focusing on the treatment of saphenous vein grafts. The sample size is too small to draw any meaningful conclusion (n = 6 patients), but the study protocol is detailed and exhaustive, including clinical follow-up at the 12th month (n = 6), and angiographic (n = 4) and OCT (n = 3) follow-up at 6–7 months. The limitations are blatantly obvious, namely the small sample size and the irregular imaging protocol compliance, but still it is a landmark in our understanding of the performance of scaffolds in non-native cardiac vessels. n nThe use of BRS in saphenous vein grafts is not a trivial issue. Bioresorbable devices have narrow overexpansion margins, limited by low rupture thresholds [9, 10]. Due to this particular feature, sizing becomes a critical step in BRS implantation. The correction of undersizing always entails a risk of scaffold rupture, and beyond a 0.5 mm mismatch in diameter the correction becomes most likely impossible [9, 10]. Accurate sizing is particularly challenging in saphenous bypass grafts, because of the usually larger diameter of the venous grafts that might exceed the size of currently available BRS. Aside from the mechanical challenges during the implantation procedure, there are additional factors that might theoretically introduce some variability in the BRS outcomes in a saphenous-graft scenario: the different structure of the vessel wall, the peculiar composition of the stenotic lesion in the venous graft or the lower wall shear-stress. These factors might modulate the vessel response to BRS in venous grafts, eventually resulting in some nuances as compared with the results extensively described for native coronary arteries. The resorption rate should not be altered depending on the vessel in which the BRS is implanted, at least theoretically, since it is a mainly hydrolysis-dependent process, not so influenced by the flow rate or by the architecture of the underlying tissue [11]. However, empirical data are still missing. n nThe current study by Roleder et al. is obviously insufficient to answer the array of open questions [5]. It is perhaps even underpowered to provide a single solid answer to any of these questions. However, it shows for the first time that neither major mechanical complications nor grossly suboptimal acute results are expected following a simple standard implantation protocol. This is of the utmost relevance, particularly because 50% of the patients underwent optical coherence tomography (OCT) during the implantation (i.e. the sizing might have been guided by the OCT measurements), but the other 50% of patients underwent a purely angiographic-guided implantation procedure. The protocol describes anyway that the implantation was guided by angiography in all cases, irrespective of the OCT imaging: the OCT pullbacks were obtained after the BRS deployment. The hereby reported results, although modest, encourage us to proceed in this direction. Regarding the other theoretical factors that could modulate the long-term outcome (tissue/lesion structure, flow conditions, bioresorption rate, etc…), we cannot infer any conclusion from the current study, too small to detect any subtle nuance, but at least the 12-month clinical follow-up is encouraging (no death, myocardial infarction or target vessel revascularisation). Again, inconclusive but encouraging. n nIn summary, this preliminary report of the OCTOPUS registry is a modest but bold step forward to become Beethoven and feel confident enough to break the elementary rules of harmony if it makes sense, i.e. to move out of the safe but narrow path of the on-label indications for BRS, expanding them to the challenging scenario of saphenous vein grafts. The authors must be congratulated for their pioneering initiative and for the high-quality scientific approach to generate evidence at all the required levels. Nonetheless, it is just a first bold step forward: we are still closer to the pupil than to the master. Further results of larger and more conclusive studies are required to shape definitely the evidence about this indication and will be celebrated by the scientific community.

Intravascular imaging, histopathological analysis, and catecholamine quantification following catheter-based renal denervation in a swine model: the impact of prebifurcation energy delivery

The purpose of this study was to evaluate the impact of prebifurcation renal denervation in a swine model and assess its safety through optical coherence tomography (OCT). Prebifurcation renal denervation with a multi-electrode catheter was performed in one renal artery of 12 healthy pigs, with the contralateral artery and kidney being used as controls. Angiograms and OCT pullbacks were obtained peri-procedurally and 1 month post procedure. Renal tissue catecholamines were quantified, and the arterial wall and peri-adventitial tissue were analyzed histologically. Intraluminal changes (endothelial swelling, spasm, and thrombus formation) were observed acutely by OCT in most of the treated arteries and were no longer visible at follow-up. Histology revealed a statistically significant accumulation of collagen (fibrosis) and a near absence of tyrosine hydroxylase labeling in the denervated artery, suggesting a clear reduction in nervous terminals. Renal tissue catecholamine levels were similar between both sides, probably due to the low number of ablation points and the renorenal reflex. The present study demonstrates that renal denervation is associated with acute intimal disruptions, areas of fibrosis, and a reduction in nervous terminals. The lack of difference in renal tissue catecholamine levels is indicative of the need to perform the highest and safest number of ablation points in both renal arteries. These findings are important because they demonstrate the histological consequences of radiofrequency energy application and its medium-term safety.

Macrophagic enhancement in optical coherence tomography imaging by means of superparamagnetic iron oxide nanoparticles

BACKGROUNDnThe ability of optical coherence tomography (OCT) to visualise macrophages in vivo in coronary arteries is still controversial. We hypothesise that imaging of macrophages in OCT could be enhanced by means of superparamagnetic nanoparticles.nnnMETHODSnWe compared the optical backscattering and attenuation of cell pellets containing RAW 264.7 macrophages with those of macrophagic cell pellets labelled with very small superparamagnetic oxydised nanoparticles (VSOP) by means of light intensity analysis in OCT. The labelled macrophages were incubated with VSOP at a concentration of 1 mM Fe, corresponding to intracellular iron concentrations of 8.8 pg/cell. To study the effect of intracellular accumulation on the backscattering, VSOP dilutions without cells were also compared. OCT pullbacks of the PCR tubes containing the cell pellets were obtained and light intensity analysis was performed on raw OCT images in polar view, after normalisation by the backscattering of the PCR tube. The backscattering was estimated by the peak normalised intensity, whilst the attenuation was estimated by the number of pixels between the peak and the normalised intensity 1 (peak-to-one).nnnRESULTSnVSOP-loaded macrophages have higher backscattering than the corresponding unlabelled macrophages (peak normalised intensity 6.30 vs. 3.15) with also slightly higher attenuation (peak-toone 61 vs. 66 pixels). The backscattering of the nanoparticles in suspension was negligible in the light intensity analysis.nnnCONCLUSIONSnVSOP increase significantly the optical backscattering of macrophages in the nearinfrared region, with minimal increase in signal attenuation. This finding enables the enhancement of macrophages in conventional OCT imaging with an easily implementable methodology.

Intravascular ultrasound-guided retrograde percutaneous coronary intervention of a chronic total occlusion

Address for correspondence: Prof. Juan Luis Gutiérrez-Chico, Head of the Interventional Cardiology Department, Klinikum Markendorf – Frankfurt an der Oder, Müllroser Chaussee 7, 15236 – Berlin/Brandenburg, Germany: tel: +49 (0) 3355 48 1454, +49 (0) 176 30585019, +34 615 319370, e-mail: juanluis.gutierrezchico@ictra.es Prof. Kinzo Ueda: e-mail: uedainkyoto@yahoo.co.jp Prof. Tae Hoon Ahn: e-mail: encore@gilhospital.com Conflict of interest: none declared Kardiologia Polska Copyright

Intimomedial Abrasion Complicating Coronary Thrombus Aspiration

A 73-year-old man referred for primary percutaneous coronary intervention (pPCI) presented with complete occlusion of the proximal left anterior descending artery (LAD) ([Online Video 1][1]). Aspiration thrombectomy was performed with an Export AP catheter (forward-facing tip, 1.09-mm inner lumen